Solar tracker

oil pan 4 · July 2018

I know everyone says they are a waste of money.

But I am looking at building them really cheap but sturdy. The monopole designs look like they are most popular, but they would be destroyed out here and I don't think I really need to perfectly follow the sun across the sky the entire day from sun rise to sun set.
I'm thinking a ground mounted system that does automatic azmith and manual altitude.
Since I'm already building ground mounts that part cost is inherent, just making the mount move is the added cost.
I was looking at 200 to 300 additional dollars to make the ground mounts trackable for each set of 1,300 watts of panels.
Why?
Well I figure they make, build and install everything solar power related based on max power output.
But you only get full power for about 3 hours out of the day and out for a few months out of the year. So if I can maximize on that output I get the most power possible for a give system. Plus I want to build a sprawling multi level solar power system eventually up to 10kw. Once I exceede 10kw I would have to shell out massive $ for a service upgrade, that has to be done by an electrician.
With trackers I can build that extra power into the system a little at a time for a total cost of $800 to $2,000. Where the service upgrade starts at $2,000. If you don't have $3,000 in cash on hand for a service upgrade don't even bother calling the electrician.

The specs on the tracker would look some thing like 100° to 125° of azimuth rotation pivoting from the middle of the panel and up to about 40° to 45° of tilt for seasonal elevation.
I may build the first one to test elevation tracking just to compare with active elevation control versus fixed.
As long as I can kind of point the panels close to orthogonal it will work really well, even if im off by 10° I'm only lose something like 1% of power.

To keep the ground mount build cost way down I was going to buy steel drill pipe from the local agricultural and tractor auction. The pipe I would use consistently goes for 70 cents to $1.20 a foot at auction. Usually right at $1 per foot.

My biggest welder is a miller model 250, about a 360lb machine that is stuck in the garage drive way area.
I'm running a dedicated welder circuit out there to my ground mount area for the buzz box, plasma, air compressors and already have a 30 amp 120v circuit out there.
I have a home made 100 amp DC Honda GX200 powered alternator welder, a 185 amp AC only buzz box, Lincoln 135 amp wire feed, 105 amp home made transformer tig.
240v powered 40 amp miller plasma cutter, about 7 grinders, portable band saw, chop saw. Cutting and forming metal is not a problem for me.
I may drag my miller model 250 out there.

The only tools I don't have for this that I could see needing would be a tube notcher and power auger.

Dave Angelini · July 2018

I don't say they are a waste of time. You can learn alot. You can also watch a time lapse of a dual axis and learn just as much.
People who build them homebrew often have problems with the actuators and wind/snow.

You can look at Array Technology and their trackers. I have been using them for over 12 years and none of the 30 or so I have bought have any problems. Zero! You might get some ideas from their site. They now use mainly a HZLA which is a bit easier than a dual axis model 250. The 250 is the number of square feet of panels the design is good for in a hurricane.

Many people virtual track offgrid to get long hours of power from the sun!

My home is around latitude 37 and at this time of year the azimuth rotation is over 240 degrees. I do not bother with the elevation axis for offgrid as it really is for grid use where every watt is used.

Good Luck!

just starting · August 2018

At 2000$ I could add a second array 1500w and any cc on the market and still have a few hundred$ Price panels first.

Dave Angelini · August 2018

There is a reason to track offgrid. Long hours of useable power before the battery. Farmers who pump water and people who need air conditioning often use tracking to avoid the next size up in battery. If you do not need that by all means stay fixed. Do both as you grow into this

Your math is off as you would still have to build a durable array.

oil pan 4 · August 2018

I will repeat it again.
Solar power systems are based on name plate rating.
10kw of installed fixed panels might generate up to 50kw per day. On trackers I might be able to do up to 70kwh. If I wanted to install 70kwh worth of fixed panels I would be at about 14kw installed, which would require a service upgrade, which the service upgrade alone would cost between $2,000 and $4,000.
So what's cheaper?
10k of panels on about a 10 to 12kw inverter, trackers.
14k of panels, probably two 7 or 8kw inverters, a $2,000 to $4,000 service up grade.
I'm thinking the trackers are looking pretty good.

mcgivor · August 2018

The plan to build and evaluate one would be a wise move, to gather data which could be used for a larger scale, some commercial trackers use GPS with software to accurately track the sun throughout the year, DIY may not achieve the accuracy so results may differ, but worth a try I guess.

clockmanfran · August 2018

Hi oil pan,

Yes a self built tracker is possible.

But there are limitations to its design before you have to start using serious amounts of materials so the tracker can handle those Hurricane wind conditions.

Over the years I have found that 2kW of panels, ie ....... 8off, 250w size, 2meters by 1 meter each, is very possible.

I design and build to a particular mantra, GOOD DESIGN TO KEEP MATERIAL USE MINIMAL, ..... KEEP IT SIMPLE, ....... MAKE IT ROBUST ...... and KEEP IT COST EFFECTIVE.

And I use basic tools, MMA Stick welder, Drill press, 9inch angle/cutter hand held and basic hand tools.

Costs.... Tracker frame unit and 1.2m x 1.2m x 1.2m concrete footing base, about ........ $350.

........... 8 PV panels, good quality, about ....... $1200.

.......... Actuator arm unit, 24volt, (its acrtually36v but 24v is great), 24 inch thrust/pull type heavy duty satellite dish type. Main problem is ingress of water to the gear box bearing's and the electric motor unit. The manufacturers say they are sealed but over a year outside ... hmm.! . So mods are required. NB, keep the rubber boots loose or the ram will jam and shred a gear. ........ Good quality ram ...... $160

......... Electric sensor and control unit. I use a East/West LED sense unit that looks for the sun every 15 minutes or so, so its not wasting your 24v, and returns and auto parks for the morning sun at low light conditions/dusk. ........ about $140

Sadly my supplier in Australia has died, and I need to have a go at the RED ROCK unit that is a kit in the US which is a very similar product.

A good quality, high input DC controller at about ......... $500.

So a complete DIY 2kW Solar Tracker is possible around the ...... $2,350 ball park. Probably allot cheaper if you shop around, but don't skimp on the actuator arm.

I also have a static frame array for PV , and the only saving is about $150 on steel materials as the concrete footings and other equipment are still required for a static array. But construction time for a static array is rapid, and there are no moving parts.

Today 2018 In general I Recommend a PV Static array, especially as the PV panels are nowadays at a very good price.

I trust my comments help.

We here are not a business we do not retail stuff. We are independent and our philosophy is to help others who ask, so hence our Non Profit small publications.

"HOW TO MAKE A LOW COST, SIMPLE AND ROBUST 2kW DOUBLE AXIS PV SOLAR TRACKER" ISBN 978-0-9935903-1-3

bill von novak · August 2018

oil pan 4 said:

I will repeat it again.
Solar power systems are based on name plate rating.
10kw of installed fixed panels might generate up to 50kw per day. On trackers I might be able to do up to 70kwh. If I wanted to install 70kwh worth of fixed panels I would be at about 14kw installed, which would require a service upgrade, which the service upgrade alone would cost between $2,000 and $4,000.
So what's cheaper?
10k of panels on about a 10 to 12kw inverter, trackers.
14k of panels, probably two 7 or 8kw inverters, a $2,000 to $4,000 service up grade.
I'm thinking the trackers are looking pretty good.

For freestanding mounts trackers can save a little money. But they're not as easy to work with as flat mounts, and of course for roof mounts there's no effective way to track.

What has doomed most trackers is the cheap cost of solar. When that extra 4KW of panels cost $8000 a tracker made a lot of sense. Now that you can get it for close to $2000 it makes less sense.

BTW many people now do SE and SW fixed arrays so they can use the smaller inverter while getting power over more of the day.

Dave Angelini · August 2018

Many people used SE and SW arrays 25+ years ago also..... Just sayin it is not new

oil pan 4 · August 2018

I was going to do flat mounts that move.

The 4kw sunny boy SPS inverter has 2 inputs so I could easily hook it up to 2 arrays a south east and south west facing array, maybe do 2.5 to 3kw per array. To buy all those panels I'm on the hook for around $1,500 minimum just for the panels then around $500 to rack them, if I build them my self, then wire conduit and disconnect, hell the disconnect alone for a high voltage DC array is up to $400.
Generally I agree "more panels are cheaper" for most people.

I have mig, stick welders and my stick welders double as my tig welders power source, drill press, 40 amp miller plasma cutter, little 4 inch grinders/paint removers all the way up to a 240v powered 9 inch grinder. Have a tractor with blade and post hole digger I can use to level the ground and dig out the post hole mounts.

I know I don't need super expensive fancy tracking, I know if I'm 10 degrees from the sun I'm giving up about 1% of solar power. As long I can stay with in 10 degrees of the sun most of the day that's good enough.

I may decide auto tracking isn't worth it and just do manual tracking, just move the panels with the changing seasons.

Dave Angelini · August 2018

If you have the skill and time to do it, you should. In my testing offgrid 20 degrees is close enough. For winter it is amazing how many times the sun peaks out for an hour and the bank gets topped off. If the array was not pointing at the sun, well

This seems to happen mostly that last couple hours of daylight up here in the mountains.

Everytime I price out a decent pole mount (for clients) that can take the wind/snow, for a 2KW array the tracker wins.
You just need to price it realistically. A couple decent manual pole mounts from the store here are $1400 ea.
https://www.solar-electric.com/dpw-solar-universal-top-pole-mount-utpm8-g.html

I do not sell/use the trackers that the store here does because I have 14 years experience with Array Technology. All of it is good!

Manually moving poles daily is an exercise in futility unless you have an Android to do it for you. Ever see Arthur the droid in the movie Passengers?

bill von novak · August 2018

Dave Angelini said:

Many people used SE and SW arrays 25+ years ago also..... Just sayin it is not new

Definitely agreed there. But the decision was a lot different 25 years ago, when panels were $5/watt.

Dave Angelini · August 2018

I will agree it was different then offgrid, and even more than 5$ a watt, but it still comes down what does it cost to make two arrays vs the cost of one tracked array.

The example I like includes the cost of quality/durably built arrays and not just laying solar panels on the ground

Unusual to use a roof offgrid also even if it was oriented correctly.

I like a 2KW size arrays because they can power a 1500 watt AC load most hours of the day if pointing at the sun.
You would probably need two fixed arrays to do this if they were fixed SE and SW.

The sticker shock of tracker cost is because most people just look at retail price. The real price is often much less. Heavy equipment like pole mounting arrays are often negotiable and is drop shipped from the manufacturer. Most all stores would never stock this type of equipment.

It really gets down to do you need long hours of useable solar power or not. I can't imagine going back to fixed solar after the last month of fires and 100F heat. Winters of not needing a generator in many places of the SW or similar places are another factor

bill von novak · August 2018

Dave Angelini said:

I will agree it was different then offgrid, and even more than 5$ a watt, but it still comes down what does it cost to make two arrays vs the cost of one tracked array.

The example I like includes the cost of quality/durably built arrays and not just laying solar panels on the ground Unusual to use a roof offgrid also even if it was oriented correctly.

Definitely agreed there - but I think that's due to off-gridders being on big plots of land where you can clear trees to ensure good exposure. And on most off-grid sites, no one really cares if you put up a few polemount arrays. (Try that with an HOA.)

Dave Angelini · August 2018

I tried that with a tv antenna and learned the HOA is going to work for me

The other thing about a roof offgrid is that most see the value in not using a roof for anything more than rainwater and keeping the rain out

oil pan 4 · August 2018

My hoa is made up of cows and horses.

Dave Angelini · August 2018

Nice !

We have deer, mountain lions, bobcats, and coyotes....

bill von novak · August 2018

oil pan 4 said:

My hoa is made up of cows and horses.

Ay, there's the difference. Mine is made up of people who aspire to be politicians but couldn't make the grade, and who deeply desire to exercise power over "their" domain.

oil pan 4 · August 2018

I think that sounds like Germany in the 1930s.

Dave Angelini · August 2018

Too bad, Politics is overrated compared to nature.

Solar tracker

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